From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from firstgate.proxmox.com (firstgate.proxmox.com [212.224.123.68]) by lore.proxmox.com (Postfix) with ESMTPS id E4D991FF165 for ; Thu, 25 Sep 2025 14:45:40 +0200 (CEST) Received: from firstgate.proxmox.com (localhost [127.0.0.1]) by firstgate.proxmox.com (Proxmox) with ESMTP id AA96820BDD; Thu, 25 Sep 2025 14:46:12 +0200 (CEST) Date: Thu, 25 Sep 2025 14:46:07 +0200 From: Fabian =?iso-8859-1?q?Gr=FCnbichler?= To: Proxmox Backup Server development discussion References: <20250924145612.188579-1-c.ebner@proxmox.com> <20250924145612.188579-3-c.ebner@proxmox.com> In-Reply-To: <20250924145612.188579-3-c.ebner@proxmox.com> MIME-Version: 1.0 User-Agent: astroid/0.17.0 (https://github.com/astroidmail/astroid) Message-Id: <1758804082.vknehzyjxx.astroid@yuna.none> X-Bm-Milter-Handled: 55990f41-d878-4baa-be0a-ee34c49e34d2 X-Bm-Transport-Timestamp: 1758804356005 X-SPAM-LEVEL: Spam detection results: 0 AWL 0.049 Adjusted score from AWL reputation of From: address BAYES_00 -1.9 Bayes spam probability is 0 to 1% DMARC_MISSING 0.1 Missing DMARC policy KAM_DMARC_STATUS 0.01 Test Rule for DKIM or SPF Failure with Strict Alignment KAM_SHORT 0.001 Use of a URL Shortener for very short URL SPF_HELO_NONE 0.001 SPF: HELO does not publish an SPF Record SPF_PASS -0.001 SPF: sender matches SPF record Subject: Re: [pbs-devel] [PATCH proxmox-backup 2/2] api: backup: never hold mutex guard when doing manifest update X-BeenThere: pbs-devel@lists.proxmox.com X-Mailman-Version: 2.1.29 Precedence: list List-Id: Proxmox Backup Server development discussion List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Proxmox Backup Server development discussion Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Errors-To: pbs-devel-bounces@lists.proxmox.com Sender: "pbs-devel" On September 24, 2025 4:56 pm, Christian Ebner wrote: > An manifest update with s3 backend will call async code, which must > be avoided because of possible deadlocks [0]. Therefore, perform all > changes on the shared backup state and drop the guard before > updating the manifest, which performs the backend specific update. > Dropping the guard prematurely is fine, as the state has already been > set to be finished, so no other api calls belonging to the same > backup task cannot perform further changes anyways. > > [0] https://docs.rs/tokio/latest/tokio/sync/struct.Mutex.html#which-kind-of-mutex-should-you-use > > Signed-off-by: Christian Ebner > --- > src/api2/backup/environment.rs | 12 ++++++++---- > 1 file changed, 8 insertions(+), 4 deletions(-) > > diff --git a/src/api2/backup/environment.rs b/src/api2/backup/environment.rs > index e535891a4..073027c51 100644 > --- a/src/api2/backup/environment.rs > +++ b/src/api2/backup/environment.rs > @@ -682,8 +682,15 @@ impl BackupEnvironment { > } > } > > - // check for valid manifest and store stats > let stats = serde_json::to_value(state.backup_stat)?; > + > + // marks the backup state as finished, so no other api calls can modify its state anymore > + state.finished = true; marking it as finished (which prevents cleanup in case the client connection disappears!) > + // never hold mutex guard during s3 upload due to possible deadlocks > + drop(state); > + > + // check for valid manifest and store stats > self.backup_dir > .update_manifest(&self.backend, |manifest| { > manifest.unprotected["chunk_upload_stats"] = stats; > @@ -692,9 +699,6 @@ impl BackupEnvironment { > > self.datastore.try_ensure_sync_level()?; before this has been called seems kind of dangerous? why not update the manifest up front, then lock the state etc.? or lock do_some_checks mark_as_finishing (new state that needs to be checked in some places) drop state update_manifest lock do_checks_again mark_as_finished ? that way it should be race-free but still safe.. > - // marks the backup as successful > - state.finished = true; > - > Ok(()) > } > > -- > 2.47.3 > > > > _______________________________________________ > pbs-devel mailing list > pbs-devel@lists.proxmox.com > https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel > > > _______________________________________________ pbs-devel mailing list pbs-devel@lists.proxmox.com https://lists.proxmox.com/cgi-bin/mailman/listinfo/pbs-devel